What happened?

I recently purchased a large mysterious snail and put it in a tank with 1 gold fish and 2 rosy minnows. I came home today to find the snail missing. I moved the tank ornaments around and found it's trap with a bit of flesh still attached and nothing else. I can't even find the shell. The gold fish is only a couple inches long. I didn't think it could injure or eat the snail. Anyone have any ideas what happened.